Advice?

Hi, im here for advice. I dont mean to offend anyone with this post. But, me and my boyfriend had sex on July 7th. Its now August 4th. My periods are usually irregular so i cant really depend on that to tell me if im pregnant or not. But i started Extremely lightly bleeding and it was brown and as i said, vert light. Usually my periods are heavy. And that brown "bleeding" only lasted 2-3 days and now im not bleeding at all. Im only 17 (18 this upcoming December). Is it possible that im pregnant? Ive been hungry alittle more that usual ive noticed and been feeling Slightly nauseous and sensitive around smells and foods.